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A012672
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arcsinh(tanh(x)*tan(x)) = 2/2!*x^2-8/6!*x^6+82592/10!*x^10...
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0
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2, -8, 82592, -608724608, 22327881339392, -1873956615576209408, 347762137588896627924992, -121417393113776577986657681408, 73797732351936752045312739712827392, -72816242431281104821128628533638537412608, 110758942324721681029366683611691936115004014592
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OFFSET
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0,1
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LINKS
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Table of n, a(n) for n=0..10.
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FORMULA
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Lim sup n->infinity (|a(n)|/(4*n)!)^(1/(4*n)) = 0.9003163161571... = abs(1/r), where r is the complex root of the equation sin(r)*(exp(2*r)-1) = I*cos(r)*(exp(2*r)+1). - Vaclav Kotesovec, Nov 02 2013
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MATHEMATICA
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With[{nn=30}, Take[CoefficientList[Series[ArcSinh[Tanh[x]Tan[x]], {x, 0, nn}], x] Range[0, nn]!, {3, -1, 4}]] (* Harvey P. Dale, Aug 08 2013 *)
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CROSSREFS
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Sequence in context: A272331 A256065 A081979 * A024340 A012667 A124075
Adjacent sequences: A012669 A012670 A012671 * A012673 A012674 A012675
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KEYWORD
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sign
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AUTHOR
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Patrick Demichel (patrick.demichel(AT)hp.com)
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STATUS
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approved
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